1. Field of the Invention
The present invention pertains to the art of cooking appliances and, more particularly, to a multi-stage catalyst for a cooking appliance.
2. Discussion of the Prior Art
In the art of cooking appliances, it has been heretofore proposed to enable an appliance to operate in a self-cleaning mode. For example, in a conventional range having a cooking cavity which can be heated by one or more cooking elements arranged within the cooking cavity to perform at least baking and broiling functions, it is known to operate one or more of the cooking elements to perform a pyrolytic self-cleaning operation in order to cleanse the walls of the cavity from grease and other food soils developed during normal cooking operations. In such a cooking arrangement, the cooking elements used to perform the cleaning process are located entirely within the cooking cavity.
In addition, it is known to provide a catalytic self-cleaning oven. In such an arrangement, the walls of the oven are coated with a catalytic material which provides for self-cleaning of the oven cavity during cooking operations. In performing any self-cleaning function, byproducts, including smoke, gases and other odorous fumes, are inherently produced. A typical oven cavity will be vented to permit the escape of these byproducts to the ambient surroundings. In some cases, a catalytic oxidation unit is provided in the vent to react with the flowing byproducts.
In still other cooking appliance arrangements, a combination of pyrolytic and catalytic cleaning is performed. Regardless of the fact that various self-cleaning systems have been proposed in the art, there still exists a need for an improved self-cleaning system for a cooking appliance which maximizes the elimination of byproducts, while also minimizing the necessary operating time for any self-cleaning mode. Particular concerns are raised in connection with the necessary operating time and byproduct elimination in a self-cleaning convection oven which essentially relies on a heated flow of recirculating air for raising the temperature in an oven cavity. In particular, there exists a particular need for an improved catalyst used to heat and vaporize grease and oil, while starting the molecular breakdown of carbon chains in various stages for cleaning purposes.